ABSTRACT:

The cemented filling body is very important structural unit in cut-and-fill stoping. Therefore, it is of important significance to forecast the catastrophe by researching the response characteristic of cemented filling body at critical state. The damage characteristics and response ratio characteristics of cemented filling body with different cement-sand ratio have been studied by acoustic emission under uniaxial compression test. The results showed that the damage threshold of cemented filling body of cement-sand ratio 1:4 is 33%~41% of uniaxial compressive strength, as for cement-sand ratio 1:8; threshold is 37%~49%. As the loading stress is over 75% of uniaxial compressive strength, the filling body with cement-sand ratio 1:4 was damaged aggressively. By contrast, the filling body is damaged aggressively for cement-sand ratio 1:8 as the loading stress over 85% of uniaxial compressive strength. The response ratio for AE accumulative events, accumulative ringing count, and accumulative energy appeared to be very small at the low stress level. However, the response ratio increased greatly at critical state for all AE parameters. Therefore, this characteristic can serve as failure omen.

1 INTRODUCTION

With the increase of the mining exploitation depth, the underground pressure activity becomes more and more frequent. Therefore, it is important to predict and forecast the failure of the underground stratum and the main structural unit. The essence of the rock material failure is the process of energy dissipation and release. On the one hand, the dissipation of energy is the power of rock material failure. On the other hand, the release of energy is the immanent cause of rock material failure. And the phenomenon of acoustic emission is nothing but the quick energy release of the rock material failure. Chen (2001) studies the acoustic emission characteristics of the sandstone during the uniaxial compression process, and the results show that: the main parameters of the acoustic emission characteristics are apparently increasing when the stress is close to the peak stress. Sun (2012) concludes that the corresponding stress of the acoustic emission uprush point of the deep layered sandstone matches to the critical point of rock specimen. Miao (2009) conducts the uniaxial circulation of loading and unloading destabilization experiment, the study finds that the response ratio of loading and unloading will dramatically increase when the rock sample approaches to the critical state.

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